Commit d94af6de authored by Stanislav Kinsbursky's avatar Stanislav Kinsbursky Committed by J. Bruce Fields
Browse files

SUNRPC: move cache_detail->cache_request callback call to cache_read() 



The reason to move cache_request() callback call from
sunrpc_cache_pipe_upcall() to cache_read() is that this garantees, that cache
access will be done userspace process context (only userspace process have
proper root context).
This is required for NFSd support in container: svc_export_request() (which is
cache_request callback) calls d_path(), which, in turn, traverse dentry up to
current->fs->root. Kernel threads always have global root, while container
have be in "root jail" - i.e. have it's own nested root.

Signed-off-by: default avatarStanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 21cd1254

net/sunrpc/cache.c

+20 −12
Original line number Diff line number Diff line
@@ -750,6 +750,18 @@ struct cache_reader { 
	int			offset;	/* if non-0, we have a refcnt on next request */

};



static int cache_request(struct cache_detail *detail,

			       struct cache_request *crq)

{

	char *bp = crq->buf;

	int len = PAGE_SIZE;



	detail->cache_request(detail, crq->item, &bp, &len);

	if (len < 0)

		return -EAGAIN;

	return PAGE_SIZE - len;

}



static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,

			  loff_t *ppos, struct cache_detail *cd)

{
@@ -784,6 +796,13 @@ static ssize_t cache_read(struct file *filp, char __user *buf, size_t count, 
		rq->readers++;

	spin_unlock(&queue_lock);



	if (rq->len == 0) {

		err = cache_request(cd, rq);

		if (err < 0)

			goto out;

		rq->len = err;

	}



	if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {

		err = -EAGAIN;

		spin_lock(&queue_lock);
@@ -1145,8 +1164,6 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) 


	char *buf;

	struct cache_request *crq;

	char *bp;

	int len;



	if (!detail->cache_request)

		return -EINVAL;
@@ -1166,19 +1183,10 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) 
		return -EAGAIN;

	}



	bp = buf; len = PAGE_SIZE;



	detail->cache_request(detail, h, &bp, &len);



	if (len < 0) {

		kfree(buf);

		kfree(crq);

		return -EAGAIN;

	}

	crq->q.reader = 0;

	crq->item = cache_get(h);

	crq->buf = buf;

	crq->len = PAGE_SIZE - len;

	crq->len = 0;

	crq->readers = 0;

	spin_lock(&queue_lock);

	list_add_tail(&crq->q.list, &detail->queue);

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